What gives you the right???

Question

I am watching Last Plant From Our Sun and I want to know what gives someone the right to say that Pluto isn't a planet, but a really large kbo? Who died and made these people gods? I don't care either way, but it just got me thinking that too many people want to be right. If you think this is interesting, hit me with a star. The most detailed answer gets 10 pnts!!!!

Answer 1

The word "planet" was created and defined by humans, so I'd say we have a right to choose what it means.

Pluto is now considered a dwarf planet.  You see, there are larger objects in our solar system (like Eris, for instance) than pluto, and those aren't considered planets either.  Recently, all of those, including pluto, were redefined as dwarf planets.

In order to be considered a planet, an orbiting body must be all of the following:

[...]a celestial body that: (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and (c) has cleared the neighbourhood around its orbit.

A dwarf planet is:

[...] a celestial body that: (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape2, (c) has not cleared the neighbourhood around its orbit, and (d) is not a satellite.

Answer 2

If you don't care, why the rant?

As it happens, there were several mistakes along the way to finding a "planet" that would account for the uneven orbit of the planets just inside it.   Finding a planet is much more important than finding a rock.  And nobody, for a long time could see way out there very well.  Now that a bunch of rocks have been found, some of which are bigger than Pluto, instead of declaring all of them planets, they decided to undeclare Pluto.

Answer 3

Because Pluto doesn't fit the definiton of a planet, they just paid attention to it a couple years ago.

Answer 4

I don't know who died to put them in that position, but the gods are the International Astronomical Union.  They have the final say on the "official" name (and classification) of every celestial object...from planets, to comets, to stars.

The simple fact is that astronomers around the world need a universal system for indentifying what is out there.  The authority for maintaining such a system was bestowed upon the IAU.  (Google it if you want the history.)

The classification of Pluto was forced by the discovery of several large KBOs.  I think it's Eris that's actually larger than Pluto.  It is likely that we are going to discover dozens of objects like Pluto and Eris in the outer solar system.  Do we call them all planets?  What if we find a hundred of them?  What if we find a thousand? (Yeah, it's possible.)

Or, perhaps, it's time that we recognize a new class of objects not entirely unlike how the asteroid belt came to be classified.

When Ceres (the first asteroid) was discovered, it was immediately classified as a new planet.  That status held for less than two years as we started to discover many more asteroids.  It made sense to call Ceres an asteroid, not a planet.

The difference with Pluto is that there was a 70 year gap before we started discovering dozens of similar bodies.  Bottom line, if Pluto had been discovered ten years ago, it would never have been called a planet to begin with.  And there's the source of the controversy.

That said, there is a group of astronomers who have proposed a "round rule" for planets.  Were this rule to be adopted, we would have 12 planets including the current eight, along with Pluto/Charon as a double-planet, Ceres, and Eris. (All of these objects are large enough for gravity to have made them spherical in shape.)

The debate isn't over, though I wouldn't make any bets that Pluto will ever regain planet status.

Answer 5

It's not that they do or don't want it to be a planet. It is the scientific facts. It's just not a planet.

Answer 6

Who gave anyone the right to call it a planet? The same people. Now they say they made a mistake.